Active Power Control Integrated With Reactive Power Compensation of Battery Energy Stored Quasi-Z Source Inverter PV Power System Operating in VSG Mode

The battery energy stored quasi-Z source inverter (BES-qZSI)-based photovoltaic (PV) power system combines the advantages of the qZSI and energy storage system. However, as the BES-qZSI is a fast-response power converter without any inertia, when applied as a grid-connected system, it leads to decreased power system inertia. The low inertia problem will degrade the system's performance and affect the system's stability. Moreover, the BES-qZSI PV power system usually employs a phase-locked loop and PR regulator to control the grid current to track the desired reference in phase with the grid voltage. These do not reflect the characteristics of frequency modulation and voltage regulation. To enhance the system's frequency and voltage self-adjustment ability, a control strategy based on the virtual synchronous generator (VSG) technique for the BES-qZSI PV power system is proposed in this article. By introducing the concept of synchronous generator, the BES-qZSI PV power system has the characteristics of the heavy moment of inertia, droop frequency active, droop characteristic of voltage-reactive power, and so on. Then, an active power control strategy integrated with reactive power compensation is proposed to implement PV generation and reactive power compensation at the same time. The simulation and experimental results verify the proposed control strategy.